Apparatus for attaching turbine blades



maar M.ly 6, 1941 A2,240,743

4UNITED STATES PATENT OFFICE APPARATUS Foa AT'rACmNG TURBINE BLADES Robert C. Allen, Wauwatosa, Wis., assigner to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Original application November 26, 1937, Serial No.

176,515. Divided and this application July 15, 1940, Serial No. 345,509

`yeldingly urging said peripheral 3 Claims. (elias-23.5)

This invention relates to a novel means,.ap paratus for and method of attaching peripheral members on a central support.

More specifically, the invention relates to a novel attachment of steam or gas turbine bladesv on a spindle, and is particularly adapted to high temperature turbines and constructions in which turbine blades are subjected to stresses approaching the elastic limit of the material thereof.4

This application is a division of applicant's parent application Serial No. 176,515, filed November 26, 1937. The turbine blade of this invention and means and method of attaching the blade to the spindle are claimed in the parent application.

It has long been known to attach turbine blades by inserting the roots of each blade in grooves provided in the turbine spindle or disk. One great objection to this type of attachment is the fact that it was necessary to provide a slot or recess in one side wall of the spindle or disk groove in order to make it possible to insert the last blade of any given row. This slot or recess was later filled in by welding or calking, but resulted in a weakened and unbalanced construction.

It is an object of this invention to provide a sturdy and simple attachment of peripheral members on a central support; and especially for turbine blades on a central spindle or disk,

It is a primary object of this invention to provide a construction characterized by uniformity of attachment throughout the row of peripheral members.

It is a further object of this invention to provide an apparatus Iorifastening peripheral members to a rotatable support, said apparatus comprising a holder for the support, a holder for a plurality of.peripheral members, andmeans for rotating said holders with respect to each other. Means may be provided on such apparatus for toward said rotatable support. 1

Further objects and advantages of this invention will appear from the following description and drawings relating to specic embodiments oi' this invention. A

In the accompanying drawings,

Fig. 1 is a cross-sectional elevation view of an apparatus used in attaching a turbine blade in accordance with this invention.

Figs. 2, 3 and 4 are cross-sectional views of various modifications of blade attachment in acmembers cordance with this invention, showing parts of disks and blades attached thereto; and

Fig. 5 is a sectional elevation view of a turbine disk with one blade in place in the annular groove thereof, the section being taken on line V,V of Fig. 2. A

VIn the embodiment of the invention illustrated in Fig. 2, .the turbine spindle or disk is provided with a groove II having side walls I2, I3. Each of the walls I2, I3\is, on its innersurface, spirally threaded as shown in Fig. 5, one or more threads I4 and intervening grooves I5 being provided.

The peripheral members or blades I6 are provided with root portions Il which t into groove II. The sides of the root portionsv are provided with projections I8 and grooves I9, which are constructed to mate with spiral thread and groove I4, I5 of walls I2, I3. These projections and grooves I8, IS may be formed on lie blades by arrangingthe blades in a circular row` such as they are to occupy .on the spindle or disk, and cutting a spiral thread in the roots of the assembled blades corresponding to spiral thread Il, 4I5 on the turbine disk. To keep groove Walls l2, I3 from spreading apart when the blade roots are threaded in place, annular projections 2D are formed'on these walls which are engaged in grooves 2| at the base of each blade root. Recesses 22 are provided at each side of the blade, for inserting a tool therein While assembling or disassembling the blades with respect to their disk support. A bearing surface 23 is provided l In this case a modied V thread is shown, but a rectangular thread such as is shown in Fig. 2

may beused. At each side of tongue 21, an an nular groove 3| is provided, which coacts with tapered tongue 2l, the narrow tip of the tongue makes entry of the tongue within groove II' easy. As the blades are further threaded on the tongue, tongue 21 advances within groove II and rthe wider portion of the tongue causes the walls of groove il to tend to spread apart. Grooves 3l prevent this spreading of the walls oi' l groove Il' beyond a desired point. It will be lblades on a supporting disk are illustrated in Fig.

1. The disk Iii is iixedly mounted on shaft 45 winch is mounted in bearing 4I. Stationary frame 42 rotatably supportsa blade-holding jig, of which lower plate 43 carries blade supporting lingers 44. A pluraliity of radial slots 45 carry slidable Woodruii' keys 46. Radially supported by plate i3 is a plurality of turbine blades i6 'supported intermediate their ends by lingers 44 and adjacent their roots by keys 46 which fit into appropriate recesses 22. The blade-holding jig is completed by an upper plate 41, also provided with slots 45 and slidable Woodruff keys 46, said plate being spaced from lower plate 43 by spacing ring 48. The plates are clamped together by suitable bolts 49. Each blade I6 is urged inward by a spring 5| mounted between the outer tip of the blade and an adjustable screw 52.

To mount the blades on a turbine disk I6, the disk is placed on shaft 40 in the position shown. A number of blades I6 su'flicient for a complete row are placed on lower disk 43 in radial positions, spacing ring 48 is mounted in place, and upper disk 41 is placed thereon and clamped to the spacing ring and lower disk 43. Spider 53 is then mounted on shaft 40 and retained thereon by any suitable means. Springs 5i are then inserted through appropriate apertures in ring 48 and backed up by screws 52 to obtain any desired compression on the springs. This urges the blades inward until the roots of the blades contact the threads of groove il The iis is now rotated, as by means of handle 54, thereby rotating the blades with respect to the stationary disk, thereby threading the blade roots along the spiral threads i4 of groove Il. This rotation is continued until bearing surface 28 bears against the bottom of groove Il, when the operation is complete.

It will be noted that when the blades are in position, as shown in Fig. 2, the blade roots are wedged in place between the bottom of groove il and the inner surfaces of threads I4, resulting in a permanently tight connection. As shown, the threads I6 may be somewhat narrower than grooves I5, preventing any possible binding during the mounting of the blades on the disk.

It will be obvious that instead of turning jig 43, 41, the jig may be held stationary andl disk ii) may be rotated with respect thereto, to thread the blades in place. It is also clear that, instead nf threading the blades on the disk individually, blade segments comprising two or more blades may be threaded thereon in similar manner.

Fig. 4 illustrates a further embodiment of the invention. In this modification, the diskI 60 is provided with` a wide groove 6I having walls 8.2, 63. Wall 62 has o nejor more-ridges and ridges and grooves 64. respectively. Groove 6i is of such width that the root 66 may be inserted freely in the groove and then moved axially of the disk to engage grooves and ridges 64, 65 and 61, 66. Then segmental calking pieces 1li, 1i and 12 are arranged in the position shown.

The other side of root 66 and the inner surface of wall 63 are provided with a spiral thread or threads 14, 15. A plurality of segmentall fastening members 16 are provided with corresponding threads 11 which engage threads 14, 15 and are mounted on the disk in the same way as are blades l5 in the construction of Fig. 2. Slots 18 are provided at the surface of segmental fastening members 16 for engagement by suitable tools for threading the fastening members into position.

While the. construction of Fig. 4 is somewhat more complicated than that of Figs. 2 and 8, it may be preferable because it avoids any possibility" of excessive strain on the blades themselves in mounting them on the disk, since in this case the force is applied to fastening members 16 instead of the blades themselves.

It will be understood that the invention makes possible a rugged construction: in which the blades are safely retained in place despite the great centrifugal forces, axial thrusts, high temperatures and pressures and vibratory forces to which they are subjected in use.

While this invention has been'illustrated as being applied to turbine blades, it is clear that the apparatus for attaching the blades may be utilized to mount any peripheral members on a central support in the manner herein disclosed. While the invention has been illustrated by specific applications, it will be understood that the scope of the invention is limited only by the claims appended hereto.

The term "disk" as used in the claims is intended to include a turbine spindle or a part thereof, such as a ring or disk.

It is claimed and desired to secure by Letters Patent:

1. Ablade-mounting apparatus comprising a support for a turbine disk, meansA independent of said disk for supporting a plurality of turbine blades in radial positions around a substantial portion ofthe periphery of said disk and in the plane thereof, and means for rotating said blade support relatively to said disk support. 2. A blade-mounting apparatus comprising a support for a turbine disk, means 'independent of said disk for supporting a plurality of turbine blades in radial positions substantially surrounding said disk and in the plane thereof, resilient means for urging said blades radially inward, and means lfor rotating said blade support relatively to said disk support.

3. Apparatus for attaching peripheral members to a central support comprising means for supporting said central support, means independent of said central support for supporting a plurality'of peripheral members in radial positions substantially surrounding said central support and in the plane thereof, and means for rotating said peripheral member supporting -means relatively to said central supporting means.

ROBERT C. ALLEN# 

